Reactive

Reactive is a term used for glasses that affect one another when used together. One classic example of this is ivory and turquoise opaque glass. A dark outline is created between the two colours when these meet on the surface of a bead. This outline is caused by the sulphur in ivory glass "reacting" with copper, the additive that gives turquoise glass its colour.

The term reactive is also used describe glass which can be manipulated by flame chemistry to produce visual effects that differ from the glass in its rod form. Many of the modern silver glass rods (predominantly produced in America) change their appearance by heating in an oxygen rich or propane rich (reducing) flame.

Striking is another method that may causes some types of glass to react and become a deeper or richer shade.